1. Field of the Invention
This invention generally relates to a control system for an occupant protection apparatus. More specifically, the present invention relates to an occupant protection apparatus having one or more of air bags.
2. Background Information
There have been known various occupant protection apparatuses that utilize air bags for protecting vehicle occupants. Typically, the air bags are arranged at driver and/or passenger seats, and are activated based on a deceleration of a vehicle.
There has been known an occupant protection apparatus in which two or more air bags are arranged at a passenger seat, In such system, a proximity sensor is provided on a dashboard to detect a position of an occupant occupying the passenger seat. How the air bags should be activated at the time of a collision of the vehicle is determined based on the position of the occupant as detected by the proximity sensor. If a distance between the occupant and the dashboard is equal to or greater than a predetermined distance, the air bags are activated substantially simultaneously. On the other hand, if the distance between the occupant and the dashboard is less than the predetermined distance, the air bags are activated sequentially.
In this known occupant protection apparatus, additional spiral cables, harnesses, connectors and other components need to be provided in order to control the operation of the two or more air bags. To install an occupant protection apparatus on a driver seat side, it is generally desirable to store these components within a steering wheel. However, it is difficult to arrange a number of components within the steering wheel due to space limitation.
One possible way of addressing such disadvantage is to reduce the number of circuits in the apparatus by having squibs share one of their circuits, on either the positive side or the negative side. However in this arrangement, to activate both of the airbags at the same time, twice as much electrical current needs to be applied to the shared circuit. Therefore, the shared circuit needs to be upgraded to a higher-standard circuit, such that the shared circuit can handle twice as much electrical current passing through the circuit without breaking it. Consequently, use of such circuit leads to an increased manufacturing cost.
In view of the above, there exists a need for a control system for controlling an occupant protection apparatus which overcomes the above mentioned problems in the prior art. This invention addresses this need in the prior art as well as other needs, which will become apparent to those skilled in the art from this disclosure.
Accordingly, an object of the present invention is to provide a control system for an occupant protection apparatus that can minimize the number of components as well as avoid an increase in the manufacturing costs by utilizing a circuit of a conventional rating as a shared activation circuit for squibs.
The forgoing object of the present invention can be attained by providing a control system for an occupant protection apparatus of a vehicle comprising first and second activating devices adapted to activate the occupant protecting apparatus; a control unit operatively coupled to the first and second activating devices, the control unit including a collision diagnostic portion that determines a level of a collision of the vehicle based on deceleration of the vehicle during the collision; a deceleration sensor operatively coupled to the control unit to provide information on the deceleration of the vehicle during the collision; a first activation circuit operatively coupling the control unit to the first activating device; and a second activation circuit operatively coupling, the control unit to the second activating device, the first and second activation circuits share a commonly connected portion; the control unit activating the first activation circuit and the second activation circuit based on the level of the collision determined with the collision diagnostic portion such that if an activation time period of the second activation circuit happens to overlap with an activation time period of the first activation circuit, the control unit activates the second activation circuit after completion of activation of the first activation circuit.
These and other objects, features, aspects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses preferred embodiments of the present invention.